1. Field of the Invention
The present invention generally relates to hand controllers and, more particularly, is concerned with a hand controller having pivot axes which minimize forearm motion.
2. Description of the Prior Art
Two and three degree of freedom hand command control systems are well known in the art. Such control systems have commonly been devised utilizing a control grip shaped to fit the operator's hand. The operator typically moves the control grip, and therewith one or more gimbals of a pivotally interconnected sequence of roll, pitch and yaw gimbals for example of a three degree of freedom system, to the right and left to control the roll of an aircraft, to the front and back to control the pitch of the craft, and to twist it clockwise and counterclockwise about a vertical axis to control the yaw of the aircraft.
In some applications, as for example in helicopter control, a fourth command axis is needed to control the up and down motion, i.e. the collective motion of the aircraft. The collective control has heretofore been accomplished either by use of a separate dedicated controller or by adding a fourth axis to a three axis (roll, pitch, yaw) hand controller so that the operator lifts the control grip vertically or pushes it downwardly to produce the desired collective control.
The various hand motions required to effect the desired control grip motion have sometimes produced cross-coupling problems, i.e. where the operator in moving his hand to produce one control movement accidentally also produces another control movement. For instance, in one prior art three degree of freedom hand controller manufactured by the assignee of the present invention and used on the space shuttle Orbiter, and proposed in the cross-references applications for use in conjunction with the controller inventions therein, there is always some forearm motion along with the hand motion.
Specifically, in this particular prior art space shuttle Orbiter hand controller, the fore-and-aft extending roll axis is located below the base of the control grip, the side-to-side extending pitch axis is located through the center of the palm of the operator's hand, and the up-and-down extending yaw axis is located through the center of the control grip. Either slight rotational, side-to-side or up-and-down motion of the operator's forearm is necessary to activate the desired motion of the operator's hand on the control grip to produce any one of these control movements.
In view of the potential for cross-coupling problems with the above-described arrangement of the roll, pitch and yaw axes relative to the operator's control grip hand in the prior art controller, a need exists for an alternative three-axis scheme which will substantially reduce the necessity for forearm motion to activate the required hand motion.